The picture above is after our Core
i7 870 (LGA-1156) processor was overclocked up to 5.19GHz using our cascade
with a -102° Celsius evaporator head temperature under
full-load. Processor VCC power draw at
these frequencies is around 160W (this is possible only due to subzero
cooling), as measured with a clamp meter installed at the 12V EPS power lead.
Study the pictures closely and you should notice something peculiar. Keep in
mind it comes from a CPU installed in the same type of socket from a particular
manufacturer.

What happens after several
extreme benchmark runs...

If you noticed something weird in
the pictures then you understand the title of our article. We have what seems to be a potentially
serious issue with proper socket loading on several P55-based motherboards when overclocking to the limit. We are of course not the only ones
experiencing the problem as several of our overclocking peers have run into the
same problem.

Normally we do not worry too much about
mishaps during extreme overclocking testing as they are typically caused by
factors outside of the supplier’s control.
The overriding concern is that we have damaged every motherboard in our
possession for the P55 overclocking (extreme) shootout as well as two very expensive
i7/870 processors. These problems are
the cause of a single component and are repeatable. As such, we thought we would provide details
on current problems and will provide an update once all of the motherboard
manufacturers affected have had a chance to properly respond.

We draw your attention to the fact
that the processor shown in this pictures exhibits signs of insufficient pin-to-pad
contact (little to no contact) in what is a rather reproducible pattern with
Foxconn manufactured 1156 sockets. As soon as an end-user mounts a CPU in a
socket and latches the clamp mechanism, each pin should leave a notable mark on
the associated pad.

We've marked locations where this does not
seem to have happened, showing what
appears to be a significant reduction in the number of VCC/VSS pins for proper
power delivery, and certainly not at the right load line resistance. Damage resulting
from highly overclocked use in these types of situations is not solely limited to the
processor; let’s take a look at what happened to some of the motherboards in
which these CPU were seated.

The random level of pin/pad contact in the VCC/VSS area is an accident waiting
to happen when the processor begins to draw current, especially when highly overclocked.

When Intel publishes socket
specifications and design tolerances, it's up to component manufacturers to
strictly adhere to them when designing, manufacturing, testing and ultimately
selling their "compliant" components. Of course, that's not to say
Intel could not have goofed when releasing their specification, leaving out a
crucial tolerance or such. It could happen, but not likely. For the time being,
let's assume that's not the case; seeing as how processors installed in sockets
built by other companies have exhibited no such issue in testing to date.

At first glance, one might be
inclined to think LGA-1156 based processors are intolerant of high-end
overclocking, almost as if by design. This is correct to some extent; a quick
glance at Intel’s white papers for socket 1156 CPU’s reveals that there are
around 175 pads for VCC compared to over 250 for socket 1366 CPU’s. This means
socket 1156 has around 66% of the current capacity of socket 1366, the caveat
being that when overclocked, processors from both platforms draw similar levels
of current.

When overclocked above 4GHz,
processors from both platforms will draw around 15-16 amps via the EPS 12V rail
to VCC, VTT and some of the other sub –system power rails under full 8 thread
load from the Intel burn test (Linx). Assuming 85% PWM efficiency, we’re
looking at power draw in the region of 130-140w to VCC on both platforms. The
facts point toward tighter current handling tolerances for socket 1156 when compared
to socket 1366, especially when it comes to non-connection of VCC/VSS power
delivery pins.

Fortunately, we think we've been
able to isolate pin to pad contact issues to one particular brand of
parts. Physical inspection and end-user
reports all but confirm the issues only affects sockets manufactured by Foxconn
at this time. The only known alternative
sockets in the wild are made by LOTES or Tyco AMP. We happen to have a couple
of boards from EVGA using the LOTES/Tyco AMP sockets and MSI/DFI using the LOTES
socket design, and thus far those boards have been issue free given highly
similar operating conditions. In fact, we’ve managed to push our LGA-1156
processors further in heavy load tests on boards made using LOTES/Tyco AMP
sockets than those made with sockets from Foxconn; something we’re not putting
down solely to coincidence.

So far, EVGA is the only company
we know that uses sockets exclusively from LOTES on their top-tier P55
boards - for example, the EVGA P55 Classified 200, model E659. This by the way
may be the onus behind the decision to market the board’s “300% More Gold
Content” socket statement as a purchasing option point. If you find yourself
shopping for an EVGA P55 FTW, model E657, you've got a 50/50 chance of buying
one with a Tyco AMP socket design (using a LOTES backplate), as
opposed to one made solely with Foxconn's, the same goes for MSI and DFI who have batches of
boards in the retail channel using LOTES sockets (although we're not entirely sure on socket specifics at this point). DFI told us earlier they have dropped usage of the Foxconn sockets completely until further notice. We hear the LOTES and Tyco
AMP sockets are in short supply, which is probably why Foxconn's been able to
fill the void in the market with what we believe to be a lower quality alternative
for the extreme overclocker.

We took one of our damaged CPU’s
and inserted it into one of the EVGA (LOTES/Tyco AMP) boards and took a few pics to show
contact scoring and a side by side compare to the original Foxconn socket
indents.

Foxconn 1156 Socket Installation

Tyco AMP / LOTES 1156 Socket Installation

Note how from a variety of angles
certain pads show no evidence of contact from a Foxconn pin at all. Both the
Tyco AMP and LOTES sockets have a larger pin/pad contact surface area leaving a
slight scuff mark in the central area of each pad. In light of this, what we will
say is that if you’re thinking of doing extreme overclocking on a board built
using Foxconn's socket 1156, think again.
Or, at least check your CPU for evidence of proper pin-to-pad
contact.

We have not had any problems
with air or water cooling overclocking up to 4.3GHz, although we do have a
i5/750 that has developed a few dark pads after a thousand hours or so of
constant overclocking. However, none of
the boards have developed pin problems so we feel very safe in saying that any problems will probably occur only in extreme overclocking scenarios.

We also realize that partial
responsibility for some of the less than acceptable CPU installations may be in
fact due user installation errors.
However, if users are screwing this up by doing nothing different than
what they've always done when it comes to handling and installing LGA-type
processors, then it's hard for us to find fault with the installer. Be aware of
this situation and study the pin imprint on the CPU pads and make sure you have
good contact on the VCC/VSS power delivery pads before pushing the system too
hard.

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275 Comments

At least _some_ ASUS boards have the LOTES socket. I just got a replacement P6T Deluxe V2 with a LOTES socket. However this was an RMA after having serious random issues with the prior board, and although I didn't check the socket brand then I suspect it was Foxconn as the symptoms point to contact problems ala this article. Since Newegg got it right after a bad first experience, I wonder if Newegg knows and has a stash of good boards if the customers RMA...

FYI, this new board works like a dream. Rock solid stable i7-920 at 3.8ghz with 12gb ram running at 8-8-8-24 timings and low voltage settings (12 gb of RAM adds significant system strain and usually lowers overclocking potential). And I'm sure I can get more out of it, as I haven't optimized it yet. I couldn't get 12 gb stable on the last board at stock speeds. Reply

My Gigabyte P44 UD4P has never enabled me to overclock much with any stability. I guess it must be the Foxconn socket. I have spent a lot of time and followed a lot of guides and it's just not reliable above 3 GHz with my i5 750.Reply